Re: Polymorphism in RDBMS

Alan wrote:
> What you've got there is wrong. If one field or the other must be null, then> you need the two tables you started with. Polymorphism is an OO concept, and> is not supported directly in an RDBMS. Why do you think you need to combine> them?

Sorry I wasn't clear. I don't plan to eliminate the group_info and
person_info tables. I do, however, need a way to associate a piece of
music with an "artist", regardless of whether the artist is a group or
an individual.

I need to "combine" polymorphism and an RDBMS because music can be
written/arranged/performed by either "groups" or people. In this case,
the real world is very much "polymorphic".